1. Field of the Invention
The present invention relates to a moving apparatus, and more particularly to a moving apparatus which is employed in an industrial robot or a numerically controlled working machine and for which a precise linear movement is required.
2. Related Background Art
Among the moving apparatus employed in such machines there are already known an apparatus for moving a rod member by supporting the rod member with plural friction rollers as disclosed in the Japanese Laid-open Patent No. 61-117043, and an apparatus utilizing a screw which is fitted with a nut member fixed to a movable member and rotating the screw to move the movable member along the screw.
As a feeding mechanism of a machine tool, the Japanese Patent Publication No. 58-54948 discloses an apparatus for friction driving a movable member with a friction roller along a guide bar. The patent discloses a feeding apparatus provided with a substrate, a guide face provided on the substrate, a movable member to be moved along the guide face, a feed drive device for moving the movable member along the guide face, a position detector for detecting the position of the movable member, and a control device for controlling the drive device in response to the signal from the position detector, which comprises providing the substrate with a friction plate for moving the movable member substantially parallel to the guide face, providing the movable member with plural driving rollers for contacting friction faces of the friction plate with equal forces on both sides, connecting at least one of the driving rollers with the feed driving device, wherein, if the friction faces of the friction plate is not parallel to the guide face, the movement of the movable member along the guide face applies a pressure to the friction plate through the driving rollers, and the friction plate is provided with a thin elastic portion so as to be elastically movable by the pressure in a direction perpendicular to the moving direction of the movable member and to have a high rigidity in the moving direction, and is positioned apart from the guide face so as to allow elastic deformation of the thin elastic portion between the friction plate and the guide plate.
Also the Japanese Laid-open Patent No. 61-230835 discloses a feeding apparatus for a machine tool, comprising a longitudinal guide rail provided over the feeding length on either of a fixed base of the machine or a movable member, a rolling unit composed of at least a pair of a driving roller and a pressure roller in rolling engagement with both sides of the guide rail, a motor for driving the driving roller through a flexible joint, pressure setting means incorporated in the rolling unit; and flexible connecting means for mounting the rolling unit on the movable member or the fixed base in slightly movable manner only in a direction perpendicular to the feeding direction, wherein the movable member is displaced by the normal and reverse rotation of the motor.
Furthermore the Japanese Laid-open Patent No. 61-260957 discloses a high precision feeding apparatus for supporting a feed rod under a necessary pressure between a small feed roller supported by a pair of back-up rollers and a pair of pressure rollers positioned opposite to the small feed roller and linearly moving the feed rod by rotating the small feed roller with a stepping motor, which comprises forming each of the back-up rollers with an integral structure of mutually separated plural plate-shaped rollers, and supporting the small feed roller with the back-up rollers in a state in which the plate-shaped rollers are mutually interlocking, whereby the diameter of the small feed roller is reduced without interference between the back-up rollers or between the back-up roller and the feed rod to achieve movement of a small amount.